Switching Order of Orbitals

[hadydamaj27]

When do you know when to switch the order of orbitals like 5s and 4d. I know that the ground-state electron configuration for silver is not [Kr] 5s1 4d10. Instead it is written as [Kr] 4d10 5s1, where the 5s and 4d order is switched. Why is this the case?

[606025647]

Before the orbitals are filled, the 5s shell is a lower energy than the 4d shell, but after they have electrons in them, the 4d shell has a lower energy level. The configuration is written in order of increasing energy level, which is why you see 4d before 5s.

[Seungri_Han_2J]

After the atomic number 20, you should switch the order of s and d orbital.

Also, for exception elements, you need to lose one electron from s orbital and give it to the d orbital (so one less electron for s and one more electron for d).